Dates and time
How to add hours and minutes
You have two lengths of time, not two clock times. You will add them, or subtract the second from the first, in this tab. 1:30:00 plus 0:45:00 is 2:15:00. This is not a time zone.
Open time duration when both lengths are written as hours:minutes:seconds. Minutes and seconds must be 0–59. Nothing is uploaded.
Open Time durationContents
Write each length as H:MM:SS
1 hour 30 minutes is 1:30:00. 45 minutes is 0:45:00. 90 minutes is 1:30:00, not 0:90:00. Minutes and seconds above 59 fail.
1:30:00 + 0:45:00 = 2:15:00. 0:90:00 is not valid. Open time duration on cv.cm
The math stays in this tab.
Open Time durationChoose add or subtract
Add joins the two lengths. Subtract takes the second away from the first. 1:30:00 minus 0:45:00 is 0:45:00.
Read the clock-style result and the total seconds
1:30:00 plus 0:45:00 is 2:15:00, which is 8,100 seconds. Copy includes both lines. An API that wants seconds wants the second line.
A longer second length makes a negative result
0:30:00 minus 0:45:00 is -0:15:00. The minus is a direction on a length. It is not a clock time before midnight.
A longer second length gives a minus. This is a length, not a clock. Keep this separate from a clock and a time zone
1:30:00 here is a length of 90 minutes. It is not 1:30 in the morning, and it does not move between New York and Shanghai.
FAQ
Can I add hours and minutes free online?
Yes. cv.cm adds or subtracts two H:MM:SS lengths in this tab. Nothing is uploaded.
What format do the times use?
Hours:minutes:seconds, such as 1:30:00. Minutes and seconds must be 0–59. 0:90:00 fails. Write 1:30:00.
What is 1:30:00 plus 0:45:00?
2:15:00, which is 8,100 seconds.
What if the second time is longer?
Subtracting it gives a negative length, such as -0:15:00. That is a direction, not a clock time.
Is this a time zone converter?
No. These are lengths of time. A clock time in a city is the time-zone tool.